Just posted this on Barefoot Ted's group, and liked it:
I approached full-time minimalist running as an experiment, and therefore was paying careful attention to how I was feeling and doing. I did only three-mile runs for quite a while, and then bumped up to 4 and then 5 mile runs. I don't think I did an 8-mile run for probably 2 months. Of course, I'd never done an 8-mile road run in regular running shoes in the previous 10 years of running, so this was quite the triumph.
But many folks (as we all know) slap on a pair of Vibrams and think they're Bikila. Those folks are going to have a rough time of it. (I did that my first run in Vibrams after reading Born to Run.)
Just as succeeding at minimalist running requires that you listen to your body, so deciding if you know if you need a coach requires you to know your self. I've taught myself a number of sports, all of which are far more dangerous than running. I've learned a cautious, scientific approach, since I hate getting hurt. So I think I'm a fine candidate for teaching myself minimalist running.
But for some folks, a coach is a good idea. If you feel like you're struggling, or something's wrong, and you can't determine how to solve the problem, get some help.
When I taught myself white-water kayaking (which is far and away the most dangerous sport I taught myself), I wasn't able to figure out how to do the eskimo roll consistently. I was about at 50% success. A good instructor showed me the trick in one try. It took about 5 minutes. But I had to know myself well enough to ask for, and take, the advice. Another fellow I know was able to teach himself an eskimo roll both with and without a paddle without a coach.
We all have different capabilities in some respects. The real trick to being a good athlete, IMHO, is in knowing yourself. And that means knowing when you need some help (maybe a coach) and knowing when you don't.